<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="./vue.js"></script>
</head>
<body>
    <div id="app">
        <div>
            <h2>{{counter}}</h2>
            <button @click="counter++">+</button>
            <button @click="counter--">-</button>
        </div>
    </div>


    <script>
        // 数据双向绑定
        const app = new Vue({
            el: '#app',
            data: {
                counter: 0
            }
        })
    </script>
</body>
</html>